1. Field of the Invention
The present invention relates to colored polyester copolymer compounds and compositions. The greenish-blue to bluish-green (cyan) colored polyesters of the invention have thermally stable colorants copolymerized therein, thus providing colored compounds and compositions wherein the colorants do not sublime, extract, migrate, or exude. The copolymerized colorants have adequate color characteristics (hue) and are stable to heat, light, humidity and a variety of other environmental factors. These compositions are particularly useful as films and fibers.
2. Description of the Prior Art
It is known in the art to incorporate dyes into polyester films as contrasting agents. Dyes in the blue to blue-green color range have primarily been chosen from the anthraquinone family of dyes due to their thermal stability. Dyes acre typically added to the polyester during processing and must be stable to the temperature and chemical environment encountered during polyester processing. Anthraquinone dyes are described in U.S. Pat. Nos. 3,488,195 and 3,849,139, which are incorporated herein by reference. However, in these cases, the dyes are admixed with the polyester and are not copolymerized with the polyester.
It is also known in the art to copolymerize certain colorants into polyesters as described in U.S. Pat. Nos. 4,403,092 and 5,372,864. Copolymerized colorants are non-migratory, thereby eliminating the problems of sublimation and interference of the dye with the film. The method disclosed for preparing copolymerizable colorants described in these patents involves the addition of hydroxyl containing sulfamido groups to the anilino substituents on the A ring of the anthraquinone of the Formula I: ##STR1##
Addition of sulfamido groups causes hypsochrornic shifts resulting in colorants with a reddish hue which are unsuitable for this invention. When incorporated in fibers or film, the known copolymerizable blue colorants flare redder when exposed to tungsten filament light as compared to daylight, which is objectionable.
It has now been found that, in contrast to the copolymerized blue anthraquinone colorants disclosed in U.S. Pat. Nos. 4,403,092 and 5,372,864, the colorants used in this invention produce cyan colored polyesters directly without having to blend them with more bathochromic colorants such as phthalocyanines. The colored polyester copolymer compositions of the present invention are economical, environmentally and toxicologically safe, and the color is fast to heat, light, high humidity and a variety of environmental factors. Thus, many of the known problems with polyesters which contain copolymerized blue dyes are overcome by this invention.